The Book of Seilah
by Timbriny
Summary: Natsu finds a strange book that called to him while at school. The moment he reads part of it he finds his live changing….but is it for the better? And who is this girl who appeared and what does she want with him? AU. Slight OOC.
1. Chapter 1

**Hey guys, how is it going? Hope everything is fine.**

 **So yeah this is my new story. I'm just trying a crack at the pairing since Seilah doesn't get that much attention and I think she is pretty interesting character.**

 **By the way, I'll be writing her name as Seilah and not Sayla.**

 **I apologize in advance for the OOC. I'll try keeping Natsu as canon as possible but since it's my first time writing with Seilah she will most likely be OOC.**

 **Hope you guys like this story and chapter and I'll shut up now and let you read it.**

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The sound of footsteps echoed through the school's hallways as a lone figure walked towards his classroom. Classes had finished a while ago and there were no other students inside the premises and the sun was already halfway though with its descend before giving place to the moon.

The student walking along the hallways at this time of the day was no other than Natsu Dragneel and don't think he is at school because he wants to. Oh no, he is at school because of one simple reason….he forgot his phone.

Natsu was known throughout school as the dense, kind of simple minded boy who despite not paying any attention during classes had pretty high grades. Natsu was a lean, muscular young man of average height with a slightly tan skin tone, black eyes and spiky pink-colored hair; although he kept insisting it wasn't pink but salmon.

Another of Natsu's trademark characteristics was his white scarf that never left his side. According to his tales, that scarf was the last gift left to him by his father before he passed away. The teen didn't know much about his father besides what his surrogate grandfather, Makarov Dreyar, had told him.

Apparently his father, Igneel, was a wealthy young business man who had made a fortune by the time he had reached thirty. He also knew that, in addition to his scarf, his father had left him all his wealth. Natsu was thankful that his father had taken such worry in making sure he had everything he needed, but the pink/salmon haired boy was determined to make a name for himself and surpass Igneel's shadow, reason as to why he only used his father's money for living expenses, never personal things Natsu needed.

After walking through the same old hallways he walked during the day, Natsu finally reached his classroom and, just like it was suppose to be, his phone was just resting there, on top of his desk.

The boy wasted no time entering the classroom and making his way towards his desk, grabbing his phone before heading out through the same path as he had came from. Natsu couldn't wait for get home and just relax, play video games or practice; he just wanted to get out of school. But apparently, fate or whatever you wanna call it had other plans for him.

As soon as Natsu placed one foot outside the classroom he heard what sounded like a voice, echoing through the hallways. The voice didn't say anything in particular, in fact, it sounded a lot more like breathing than anything else.

"What the hell?" Natsu inquired out loud, as he let his phone slip inside his jeans pocket. He was pretty sure he had just heard someone breathe but there was no way another student, or person for that matter, was at school at that time so he decided to just stay still for a moment and see if he heard that breath again.

A few seconds passed by and no sounds were heard. Natsu convinced he had heard things, scratched his head in confusion. "I must be going senile sooner than I though." He let out as he started walking through the hallways back to the school's entrance. "I gotta stop drinking that sake gramps give me whenever I go over, I'm pretty sure it's killing my brain cells…"

Natsu kept walking along the hallways, hands in his pockets as he made his way. Besides that one account, he hadn't heard anything else besides his own footsteps. That, however, changed as soon as he passed in front of the school's library door.

For the second time in the past minutes, Natsu heard what sounded like breathing. This time however, he had no doubt he had heard right. "Is it really someone else at school at this time?" He asked himself, as he faced the library's door, place from where he was sure the sound had come from.

Natsu didn't know why, but for whatever reason, he felt drawn to that room which struck him as very odd. The only time he had gone inside the library was when he needed a quiet place to sleep, never to actually search for a book or study…

Shrugging, thinking no harm would come from taking a peek inside and see who else was at school with him. Removing his hand from his jean's pocket, Natsu grabbed the door's handle and opened it slowly.

Sticking his head inside to look, Natsu quickly became aware that the level of the breathing sounds had increased, which told him that, whoever it was that was at school, was defiantly inside that library.

"Hello?" The pink haired teen called out in the hoped of a quick answer that would tell him who else was there. His interjection was met with no reply which only intrigued him more. "Anyone in here?" He tried again, this time letting himself in and closing the door behind him.

The library wasn't the most lighted place of all time, and the fact the sun had pretty much gone into hiding a few minutes ago, the library was as dark as a room could possibly get.

Removing the phone from his pocket, Natsu unblocked it and quickly opened the flashlight app. The boy sniggered when light came out of his phone, raising his hand so he could face it forward as he walked. "And that stupid stripper said this app was useless….Ohhh how I wish I could rub this in his face right now."

Despite the fact he had only went over there to sleep, Natsu had a pretty good idea of the library's layout which helped him avoid any chairs or tables as he walked around. Most would think he was just walking aimlessly but Natsu was actually following the breading sounds which had been getting louder and clearer the more he moved into the library.

The more he followed the sounds, the more he found himself away from the door from where he had gotten into. Looking around as he went Natsu took notice that he must have reached a section of the library that not many people had visited. The shelves were clearly older than the ones right by the door and all the books were very old, some of which the cover had already started to fall off.

"I had no idea the library was this big…..or this old for that matter." Natsu stated out loud as he finally reached the place from where the breathing sounds were coming from.

Right in front of him was what could only be the oldest and most degraded shelve that existed. The wood had lost most of its dark brown color and had been replaced by countless species of mold and fungus.

Despite the shelves' appearance, Natsu's attention was drawn somewhere else. More precisely, to a book resting on the same shelve, right about his eye level. Making sure he wasn't hearing things, Natsu turned his head so his ear could face the book.

Natsu could admit he had seen pretty weird things inside this school, but never had he imagined he would find a book breathing…

Surprised by such revelation, Natsu turned his face back towards the book and read the title presented on the speed bump. "The Book of…Seilah."

The moment those words left his mouth, a strong gust of wind blew past the library, Natsu having no idea from where it could have come from since he had closed the door on his way in.

Refocusing his attention on the book, Natsu struggled with himself on whether to pick it up or not. Shrugging his shoulders, thinking nothing bad ever came from reading a book, Natsu reached out and pulled it out of the shelve.

Since he had no means of being able to read it where he was right now seeing as one of his hands was busy with his light source, Natsu carried himself and the book to the library's closest table.

Placing the book on the table and letting himself fall down on the chair, a shrieking noise filled the library as the wood creaked under Natsu's weight. Apparently, that was possibly the oldest chair in the world….

Holding his phone above the book with one hand so he had enough light, Natsu took a deep breath before turning the cover.

Most books, on the first page, had a note from the author to the reader. And as such, this one had too, however Natsu quickly found this note completely different from the other. "If you reached this point you are braver than most but beware, everyone who read what follows couldn't believe what they saw and that drove them mad; and eventually to death…." Natsu read out loud, swallowing as he finished the sentence, a gulping noise echoing around him.

"People died from reading this book?" The teenager inquired out loud. "What the fuck is this?!" He continued, a little outraged. Natsu was never one to keep his temper and the idea of people dying really pissed him off.

With one swift movement, he turned the page, only to come across what looked like another note. Deciding there was no harm in reading it our loud, Natsu started. "I hereby summon thee. May you come forth and do my biding. Come forth and serve me. Come forth, Seilah!"

The moment Natsu said those words, out of nowhere, the book in front of him exploded, sending out of the chair and back into a book shelve a few meters behind him.

A little out of himself from the collision Natsu couldn't register much, but he could clearly see the cloud of dust that had formed where the book had once been. The teen didn't even register that light seemed to have found its way to the library. As seconds passed by the cloud dissipated until it completely disappeared, revealing only something that Natsu never thought he would see.

Standing right in front of him a girl had appeared. First taking notice of the girl's face, Natsu was met with her most distinct feature: two large gold-looking horns protruding from the sides of her head and pointing upwards. Subconsciously placing that in the back of his mind Natsu continued examining the girl in front of him.

She had an hourglass figure with large breasts that were enough to make him blush. Upon her head was a white band which separated her black hair, framing her bangs from her hair below the band. Worn on her forehead was a small circular tattooed symbol with a small dot on the inside surrounded by several dots around the top. Tied around her neck was a small white colored strap. Meanwhile, the rest of her attire consisted of a very revealing beige colored leopard-printed kimono with decorative marks on her shoulders. Said kimono was wrapped around her torso with a thick, decorative yellow ribbon that was tied behind her back. This outfit was complemented by thigh-high socks that revealed hers heels and toes.

Not believing what had just happened Natsu quickly shook his head from one side to another with his eyes closed still convinced he was seeing things from the explosion. Not taking notice of the girls moving, Natsu only stopped shaking his head when he felt two hands grab his shoulders and pulling him up.

Standing on his own legs, Natsu opened his eyes, only to come across the most beautiful thing he had ever seen so far. Plastered on the girl's face was the most radiating smile one could ever hope to come across. "Are you alright, master?" The girls asked, her smile never faltering.

"Mas…? Whaa…? Who ar..? "Natsu tried to speak but his mind had other plans. He was still taking the information in but his mouth already wanted to ask things.

Gazing into the girl's purple eyes, Natsu found himself relaxing. Taking a big breath before continuing, Natsu calmed himself down under the girl's gaze.

Slowly raising his hands, Natsu grasped the girl's ones and brought them down from his shoulders. Once that was done, took a small step back to gain some distance between the two.

"I realize you have many questions…" The girls spoke, a neutral expression on her face, however Natsu couldn't help but notice how sweet her voice sounded, despite the fact he felt a tinge of sadness in it. "Well ask away, I'll clear your doubts, master."

Much calmer than what he was before, Natsu had grasped what questions he needed answered. "Who are you?" He asked with a neutral tone.

"My name is Seilah, but you can call me whatever you want, master." The now identified Seilah spoke, taking a vow before rising back up.

"Why do you keep calling me master? I didn't do anything do deserve that, Seilah." Natsu proceeded, his hands now in his pockets. He didn't know why but he just didn't feel any ill intend from this girl, Seilah.

"Because you are my master. When you read my book you summoned me and I became yours to serve." Seilah responded her hands behind her back as she faced Natsu.

"What do you mean I summoned you? You are not human?" Natsu inquired, lifting an eyebrow as he placed the question.

"No, I'm not human, master, I'm a demon. Seilah, of the Chill Moon." She spoke, subconsciously lowering her head slightly as if she had done something wrong.

Natsu was lost at words. Sure he had a pretty good idea this girls wasn't human, if the horns on her head were anything to go by, but a demon? He truly never saw that one coming.

"Okay….so I'm your master? And you are my demon? What are we suppose to do then?"

"That his for you to decide, master. Your every wish will be done, you need only voice it." Seilah admitted, her head rising back.

"Nah.." Natsu said without a care in the world. To say his answer surprised Seilah would be an understatement. She was beyond surprised, she was flabbergasted.

"Master?" Seilah inquired not following Natsu's train of thought.

"I don't need someone to do everything I wish. I'm happy as I am right now." Natsu said plainly. Listening to Natsu's words, Seilah's expression turned to a sad one.

"So you don't need me and want me to go away. Is that it, master?" She inquired her head falling once again.

"Of course not!" Natsu exclaimed, making Seilah's head rise faster than light. "I want us to be friends. And drop the whole master thing…" As he said this, Natsu extended his hand towards Seilah. "I'm Natsu, nice to meet you Seilah." Natsu told her, his grin being able to light the whole world if needed be.

Seilah didn't know what to do. None of the previous people that had summoned her had taken this attitude. She quickly found herself supporting slightly pinked tinted cheeks as she gave Natsu handshake he offered, a smile present on her face that could rival Natsu's grin.

' _Thank you, mas…Natsu'_

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 **So? How was it for first chapter?**

 **Anyone got that The Mummy reference? If you did you are awesome.**

 **This was the first chapter hence its length. The next ones probably won't be as big but yeah. I also don't know when I'll be able to upload the next one, so please just bear with me.**

 **Tell me what you thought about this chapter on the reviews. Like always follow and favorite and I'll see you guys next time, you rule!**


	2. Chapter 2

**Hey guys! How are you all? Hope everything is fine and perfect.**

 **First of all, I'm really sorry for all time between uploads, my life has been quite the busy one, school and what not, so I hope you can forgive me for not uploading as fast as you probably want.**

 **Second of all, I can't believe this story got so many nice reviews right out of the bat, I never imagined, thank you guys!**

 **I don't have that much to say right now, so I'll shut up and let you guys enjoy this chapter.**

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Something that Natsu loved doing, not that he would admit it to anyone, ever, was pretend to be a real-life ninja. Jumping from building to building, moving through the shadows and mastering the art of silence. Right now, that was what was happening.

Ever since he left the library with Seilah behind him, Natsu had been pretty much throwing himself backwards against the walls and quietly moving along it.

Seilah, not understanding in the slightest what her master, no! friend was doing just walked like she always did, occasionally sparing a few glances at Natsu, each and every time wondering if he was playing with a full deck.

Despite these thoughts about the pink haired teen, the demon was happy, happier than she had been in a long time. From the moment they talked, Natsu had showed her nothing but kindness. Before she could do anything about it, a smile found its way towards her face as she recalled the past minutes.

 _A few minutes ago….._

"Nice to meet you as well, Natsu." Seilah smiled as the two shared a handshake.

"So Seilah what can you tell me about this whole situation? I'm still trying to catch up on a few things…." Natsu scratched his head when the two broke off.

"Well, when you read my book out loud, the magic imbedded within the writings activated and I was summoned to this world." Her voice, contrary to what it had been a few moments ago, had no hint of sadness.

"Yeah okay…that you had already told me, but what do you mean by 'to this world'? Are you not from Earth?"

"I am not." Seilah answered, nodding.

"Then where are you from?" Natsu inquired. One could not tell from the look on his face but deep inside his thoughts were a rumbling mess.

"It is hard to explain, mas…I mean Natsu." She admitted, not sure how could she explain something that, in fact, didn't have any logical explanation. "I'm not from this world, but I'm not from any other world…"

"W-what? Then where are you from!?" Natsu inquired, his voice coming out a little stronger than what he had intended.

Not controlling her actions and moving on instincts acquired from past experiences, Seilah flinched when she heard Natsu's voice. Completely understanding what he had done, Natsu's face became one of regret.

"I'm sorry, Seilah, I didn't mean to scare you or anything like that." Natsu said as he raised one hand to place it on her shoulder. However when he saw her flinch yet again and shut her eyes in the process he decided against it and placed the hand inside his jean's pocket.

Moving her head slightly after opening her eyes, Seilah spoke, her voice now a little different from the previous one. "It's alright, Natsu….it's not your fault." As a resource to ensure the pink haired teen everything was fine, she flashed him a small smile, small but all one hundred percent true.

"Like I was saying, I'm not from this or any other world, I'm from a world between worlds, but inside that world nothing really exists."

If Natsu's train of thought wasn't confused already, now it sure was. Being caught completely off guard, the teen could do nothing but open his mouth in amazement. "H-how does that work then? If you come from a place where nothing exists, how are you here right now?"

"Nothing exists inside _that_ world, but when you summoned me you materialized me, you pulled me out of that world of nothingness and made me something." Seilah explained, her face showing a radiant smile as she mentioned what he had done for her.

"So…so I created you?" Natsu asked, his voice depicting his confused thoughts perfectly.

Shaking her head no, Seilah couldn't help but giggle at how innocent Natsu sounded. "No. I already existed but since I was inside _that_ world I had no material from. When you summoned me to this world, a place where you can touch and feel thins, you gave me form."

Not answering right away Natsu kept himself quiet as he needed a moment alone with his thoughts. "So…basically I pulled you from another world into this one, where in this one you took form?"

"That's right." Seilah confirmed, nodding her head.

"So I summoned you!" Natsu said, a radiant smile appearing on his face. "Ahhhhh now I get it."

 _'T-that was the first thing I said…."_ Seilah thought to herself as her face took hints of the "are you kidding me" face.

"Now that that's out of the way, where do you go from here, Seilah?" Natsu inquired, his mood now one of pure joy as he had just found something no one ever could.

"Since you were the one who summoned me I'll go where you go Natsu." Seilah answered, not fully grasping the boy's question.

"Well I'm going home now so…." Natsu started, hoping Seilah had the knowledge people just don't go to other people's house out of the blue.

"So I shall go with you." She answered plainly, the smile present on her face showing she had nothing but innocent thoughts on her mind. Despite what Natsu might think, they still were Master and Demon, and it was her duty, her only duty, to always accompany her master, unless told otherwise.

Of course Natsu being the nice and friendly guy he was he couldn't bring himself to say she couldn't come. "Arghh fine, follow me." Natsu breathed out as he headed towards the library's door.

 _Present time…._

"Say Natsu…" Seilah called out as the duo stopped in the corner between always and Natsu stuck his head out so he could see if the coast was clear.

"Yeah Seilah?" He inquired, turning his head in her direction.

When the two came face to face Seilah completely lost it and broke out giggling. Never in her long life time had she seen something like that.

"What? What is it?" Natsu asked, completely left out of what was happening. His question, however, was only met with giggles. "What's so funny?"

"Y-y-your…" She tried to speak but her giggles kept getting in the way of her words.

"My what?"

"Your face." She finally said it. "W-why are you wearing the scarf like that?"

Apparently, in those few minutes she had spaced out, Natsu had removed his scarf from around his neck and placed it around his head, only his eyes and nose sticking out.

"What's the matter with it?" Natsu asked, offended despite he didn't show it. "I'm a ninja, I need to dress like one."

Seilah didn't think she could manage anymore giggles but that soon changed when she heard her answer as another round left her mouth.

"W-why are you _trying_ to be a ninja?" She asked after her giggles had subsided enough.

"First of all." Natsu lifted his index finger. "I'm not trying, I'm _being_ a ninja." Despite finding his answer hilarious and somewhat cute, Seilah didn't giggle this time, only let her smile grow a little bigger. "And second." Natsu lifted his middle finger. "We need to be ninja if we don't wanna be seen."

"Why wouldn't we wanna be seen?" Seilah asked, the true purpose of his statement eluding her completely.

"Why? What would people think if they saw you walking around?" Natsu stated, jerking his arms in her direction to make his point. "No offense, but you are a demon and people _will_ freak out if they see you."

"That's what you are worried about?" Seilah asked surprised.

"You are not?" Natsu asked, his face taking up a lost expression.

"You don't have to worry about that. Only the one who summoned me can see me." Seilah explained.

"Ahhhhhh that makes sense." Natsu breathed out, making it sound like a billion light bulbs lighted up at the same time inside his brains. "You could have just said so from the beginning…." He continued, removing his scarf in the process from around his head and placing it back on his neck.

Giggling at his response, Seilah apologized. "Sorry. I had no idea you were worried about that."

"It's fine really, don't sweat it." Natsu answered and in kind showed her a smile that told her he was indeed okay with what had happened.

Since it was no longer necessary to walk ninja style, as Natsu would say it, the two quickly made their way across the school, then the streets and finally reached Natsu's place.

Not much light was present at the time, but from what little she could see, Seilah came to the conclusion Natsu's house was at least two stories high. Following Natsu inside as he unlocked the front door, Seilah was met with only darkness, a circumstance that quickly changed as Natsu pressed the switch and the house found itself illuminated.

"Seilah." Natsu called, grabbing her attention to him instead of the walls and ceiling. "I'd love to show you around the house, but I guess today's news was a lot to take in and I'm tired." He admitted, apparently and, contrary to popular believes, even Natsu had limited stamina. "Is it alright if I show you around tomorrow?"

"Of course. It is as you wish Natsu."

"Great, now just follow me and I'll show you where you'll sleep." Natsu said as he started walking up the stairs to the second floor. Compelling to his wishes, Seilah followed him and soon found herself in what could only be Natsu's room, if the innumerous posters and video games were anything to go by.

"Since the guest room it's not ready, you'll take my bed and I'll crash on the couch, okay?" Natsu asked rhetorically.

"But.." Seilah started, but never got to finish her sentence.

"No no no, no 'buts'." Natsu stated. "I'm your master and I'm telling you to sleep here." He didn't like using the 'master card' but he could tell from the look on Seilah's face she wasn't gonna drop the subject so he figures it was best to ended it fast.

"As you wish, master." Seilah said as she took a bow.

"Grahhh, stop with the master." Natsu breathed out, although a chuckle followed as he started closing the door behind him. "Good night Seilah."

"Good night Natsu." She answered him and the door closed as soon as she finished speaking.

Since her master had told her to sleep there, she was gonna do it, so Seilah took off her thigh-high socks and proceeded to remove her kimono as well. She might be a demon, but she was still a girl and no girl likes to get her clothes all wrinkled.

Standing nude as the day she was born, Seilah realized the weather was colder than what she thought. Sparing a few glances around the room, the spotted Natsu's closet and made her way towards it.

Picking up a plain white shirt Seilah struggled with herself on whether or not to wear it. The shirt belonged to her master and not asking for permission might be taken as an insult. Struggling with herself for a few minutes she decided that since the circumstances demanded it so, Natsu would understand.

Without a second more to lose, Seilah threw on the shirt and couldn't feel more comfortable with it. It was big enough to sustain her ample breasts and long enough to almost reach her knees, completely covering her.

Making her way towards Natsu's bed, after shutting off the room's lights, she quickly laid upon it.

'Natsu is for sure the nicest of my masters so far…..' She thought as the biggest smile appeared on her lips. 'He even offered me his bed even though I don't require sleeping.' On this last thought a giggle was heard before everything went silent and the night passed.

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 **So? What did you guys think? Tell me about it in the reviews.**

 **Just so it doesn't get confused, if you have doubts about anything just PM me and I'll see to it. By the way, Seilah doesn't require sleeping, but that doesn't mean she can't sleep.**

 **Like always, review and follow. It helps out a lot.**

 **Once again sorry for the long wait, I'll try to be quicker next time.**

 **See ya soon guys, you rule!**


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